Binary and Multiple Stars: Crash Course Astronomy #34

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Double stars are stars that appear to be near each other in the sky, but if they’re gravitationally bound together we call them binary stars. Many stars are actually part of binary or multiple systems. If they are close enough together they can actually touch other, merging into one peanut-shaped star. In some close binaries matter can flow from one star to the other, changing the way it ages. If one star is a white dwarf, this can cause periodic explosions, and possibly even lead to blowing up the entire star.

Crash Course Astronomy Poster:

Table of Contents
What are binary stars? 0:51
Merging peanut-shaped stars 6:52
Close binaries begin to flow into one another, sometimes blowing up the star 8:29

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Big Dipper [credit: Rogelio Bernal Andreo]
Sirius [credit: NASA, ESA, H. Bond (STScI), and M. Barstow (University of Leicester)]
Sirius A and B [credit: NASA/SAO/CXC]
Clashing Winds (video) [credit: NASA’s Goddard Space Flight Center]
The Radial Velocity Method (artist’s impression) [credit: ESO]
Mizar+Alcor [credit: Wikimedia Commons, Thomas Bresson]
Polaris [credit: NASA, ESA, and G. Bacon]
Does the Sun Have Long Lost Siblings? [credit: SciShow Space]
Clashing Winds (image) [credit: NASA/C. Reed X-ray images courtesy of NASA/GSFC/S. Immler]
Artist’s impression of the pulsar PSR J0348+0432 and its white dwarf companion [credit: ESO/L. Calçada]
Artist’s impression of eclipsing binary [credit: ESO/L. Calçada]
Artist’s impression of the yellow hypergiant star HR 5171 [credit: ESO]
Nova [credit: NASA, Casey Reed]
Artist’s impression of RS Ophiuchi [credit: David A. Hardy/ & PPARC]
An artist’s impression of Sirius A and B [credit: NASA, ESA and G. Bacon (STScI)]
Artist’s impression of vampire star [credit: ESO/M. Kornmesser]
Type Ia supernova [credit: Walt Feimer, NASA/Goddard Space Flight Center]


NcGNova says:

Im watching this so i dont have to goto class

Nigama Yaratapally says:

Then, does it mean that the sun, when born, was larger then and more powerful than what we see right now ?

Cxeri93 says:

how do we not know its just dark matter that keeps them floating around in circles

Lily q says:

i have a question, u said those 2 stars orbit each other every 11 mins or so which blows my mind. But if space time is everywhere wouldnt the time be different for the stars? like for us its 11 mins but for them its like a century or something longer than what we see

Andy Venom says:

Binary stars are so weird. How in the hell do they just not bump into each other and blow up?

Wrong Collective says:


Keonwoo Park says:

What if ancient super advanced civilizations somehow "constructed" these pentuplets and sextuplets of stars as monuments of their civilization.

Darth Vader says:

6:32 you spoke the opposite of what's true. brightness shouldn't drop when fainter start goes behind the bright.

varun mj says:

and if the white dwarf undergoes a supernova then what are we left with?
is it a pulsar from white dwarf or what?
i am confused!!!!!!

rani johanes says:

But our star companion nemisis is so far away from the sun

rani johanes says:

Do you know that our sun is a two star binary system

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